This specification covers alloy steel and stainless steel bolting material for pressure vessels, valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications. Ferritic steels shall be properly heat treated as best suits the high temperature characteristics of each grade. Immediately after rolling or forging, the bolting material shall be allowed to cool to a temperature below the cooling transformation range. The chemical composition requirements for each alloy are presented in details.

Four Properties of Alloy Steel Fasteners

1. High temperature resistance. For high hardness, the fasteners has strong oxidation resistance. It cannot work under high temperature and cannot be interfered by high temperature. If the fasteners is passivated after being made out, the temperature resistance will be better.

2. Physical properties. Alloy steel fasteners has higher specific resistance. The specific resistance of Alloy steel is higher than that of carbon steel by five times. Standard parts have an expansion factor. Through experiment, if the temperature is higher, the expansion factor of Alloy steel fasteners will be improved definitely.

3. Stress capacity. Alloy steel fasteners can endure moderate stress. Although it cannot be compared favorably with high strength bolt, the fasteners can still meet the common requirements.

4. Mechanical properties. High rust resistance and corrosion resistance have close relationship with the features of Alloy steel. For standard parts developing constantly, mechanical properties of Alloy steel fasteners will be enhanced further.

Mechanical Properties - Alloy Steel Fasteners

Bolts -Grade Identification Markings

Grade

Size

Tensile ksi, min

Yield, ksi, min

Elong, %, min

RA % min

B7

Up to 2-1/2

125

105

16

50

2-5/8 - 4

115

95

16

50

4-1/8 - 7

100

75

18

50

B8 Class 1

All

75

30

30

50

B8M Class 1

All

75

30

30

50

B8 Class 2

Up to 3/4

125

100

12

35

7/8 - 1

115

80

15

35

1-1/8 - 1-1/4

105

65

20

35

1-3/8 - 1-1/2

100

50

28

45

B8M Class 2

Up to 3/4

110

95

15

45

7/8 - 1

100

80

20

45

1-1/8 - 1-1/4

95

65

25

45

1-3/8 - 1-1/2

90

50

30

45

Material Chemical Composition

Element

B7 (AISI 4140)

B8 (AISI 304)

B8M (AISI 316)

Carbon

0.37 - 0.49%

0.08% max

0.08% max

Manganese

0.65 - 1.10%

2.00% max

2.00% max

Phosphorus, max

0.035%

0.045%

0.045%

Sulfur, max

0.040%

0.030%

0.030%

Silicon

0.15 - 0.35%

1.00% max

1.00% max

Chromium

0.75 - 1.20%

18.0 - 20.0%

16.0 - 18.0%

Nickel

8.0 - 11.0%

10.0 - 14.0%

Molybdenum

0.15 - 0.25%

2.00 - 3.00%

Recommended Nuts,Bolts & Washers

Bolt Grade

Nuts

Washers

B7

A194 Grade 2H

F436

B8 Class 1

A194 Grade 8

SS304

B8M Class 1

A194 Grade 8M

SS316

B8 Class 2

A194 Grade 8

SS304

B8M Class 2

A194 Grade 8M

SS316

ASTM A194

The ASTM A194 specification covers carbon, alloy and stainless steel nuts intended for use in high-pressure and/or high-temperature service. Unless otherwise specified, the American National Standard Heavy Hex Series (ANSI B 18.2.2) shall be used. Nuts up to and including 1 inch nominal size shall be UNC Series Class 2B fit. Nuts over 1 inch nominal size shall be either UNC Series Class 2B fit or 8 UN Series Class 2B fit. High strength ASTM A194 grade 2H nuts are common in the marketplace and are often substituted for ASTM A563 grade DH nuts due to the limited availability of DH nuts in certain diameters and finishes.

Each alloy shall conform to the chemical composition requirements prescribed. Hardness tests, proof of load tests, and cone proof load tests shall be made to all nuts to meet the requirements specified.

Grades Covered Under Astm A194

7

Quenched & tempered alloy steel heavy hex nuts

7M

Quenched & tempered alloy steel heavy hex nuts

A194 Mechanical Properties - Alloy Steel Fasteners

Grade Identification Marking5

Specification

Material

Nominal Size, In.

Tempering Temp. °F

Proof Load Stress, ksi

Hardness Rockwell

See Note

Min

Max

ASTM A194 Grade 4

Medium Carbon Alloy Steel, Quenched and Tempered

1/4 - 4

1100

175

C24

C38

1,2

ASTM A194 Grade 7

Medium Carbon Alloy Steel, Quenched and Tempered

1/4 - 4

1100

175

C24

C38

1,2

ASTM A194 Grade 7M

Medium Carbon Alloy Steel, Quenched and Tempered

1/4 - 4

1150

150

159

237

1,2,3

NOTES:

The markings shown for all grades of A194 nuts are for cold formed and hot forged nuts. When nuts are machined from bar stock, the nut must additionally be marked with the letter 'B'. The letters H and M indicate heat treated nuts.

Properties shown are those of coarse and 8-pitch thread heavy hex nuts.

Hardness numbers are Brinell Hardness.

Nuts that are carbide-solution treated require additional letter A - 8A or 8MA.

All nuts shall bear the manufacturer’s identification mark. Nuts shall be legibly marked on one face to indicate the grade and process of the manufacturer. Marking of wrench flats or bearing surfaces is not permitted unless agreed upon between manufacturer and purchaser. Nuts coated with zinc have an asterisk (*) marked after the grade symbol. Nuts coated with cadmium shall have a plus sign (+) marked after the grade symbol.

DM Special Steel Ltd s manufacturer, exporters and suppliers of industrial fasteners in alloy steel grades in various shapes and sizes. Our product range includes various types of steel fasteners such as Bolt, Nuts, Washer, Screws, Stud Bolt, Threaded Bars and more.

Alloy Steel fasteners manufactured by us are of high quality and are offered in standard sizes ranging from M10 TO M100 and also in custom length.

We are leading suppliers of alloy steel fasteners, high tensile fasteners to various industries such as oil and gas, petrochemicals, waste water treatment, plumbing, heat exchanger, power generation, pulp and paper manufacturing, and food processing industry among others. Our specialty is to manufacture and supply higher alloyed stainless steel fasteners in special grades such as Duplex fasteners, 904L fasteners, Monel Fasteners, Alloy 625 fasteners, Alloy 20 fasteners, Inconel 718 threaded rods and other special grades on customer demand.

Alloy Steel Fasteners Marking
Our products like Alloy Steel Fasteners are packaged to make sure that there’s no damage throughout transit. Just in case of exports, customary export packaging is completed in wooden boxes or cases. All Alloy Steel Fasteners are marked with Trademark (Company’s LOGO), Grade, Size and Lot No. On requests we can do custom marking on our products.
Alloy Steel Fasteners Test Certificates